Effects of a novel potent melanin-concentrating hormone receptor 1 antagonist, AZD1979, on body weight homeostasis in mice and dogs.

Background And Purpose: Melanin-concentrating hormone (MCH) is an orexigen, and while rodents express one MCH receptor (MCH1 receptor), humans, non-human primates and dogs express two MCH receptors (MCH1 and MCH2 ). MCH1 receptor antagonists have been developed for the treatment of obesity and lower body weight in rodents. However, the mechanisms for the body weight loss and whether MCH1 receptor antagonism can lower body weight in species expressing both MCH receptors are not fully understood.

Discovery of (3-(4-(2-Oxa-6-azaspiro[3.3]heptan-6-ylmethyl)phenoxy)azetidin-1-yl)(5-(4-methoxyphenyl)-1,3,4-oxadiazol-2-yl)methanone (AZD1979), a Melanin Concentrating Hormone Receptor 1 (MCHr1) Antagonist with Favorable Physicochemical Properties.

A novel series of melanin concentrating hormone receptor 1 (MCHr1) antagonists were the starting point for a drug discovery program that culminated in the discovery of 103 (AZD1979). The lead optimization program was conducted with a focus on reducing lipophilicity and understanding the physicochemical properties governing CNS exposure and undesired off-target pharmacology such as hERG interactions. An integrated approach was taken where the key assay was ex vivo receptor occupancy in mice.

Partial agonist activity of R3(BΔ23-27)R/I5 at RXFP3--investigation of in vivo and in vitro pharmacology.

Relaxin family peptide receptor 3 (RXFP3) is a G-protein coupled receptor mainly expressed in the brain and involved in appetite regulation. Previous studies in lean Wistar rats during the light phase have shown that the chimeric peptide R3(BΔ23-27)R/I5 suppresses food intake stimulated by an RXFP3 agonist, but has no effect on food intake when administered alone. We wanted to further investigate if R3(BΔ23-27)R/I5 on its own is able to antagonize the basal tone of the relaxin-3/RXFP3 system and therefore characterized the pharmacology of R3(BΔ23-27)R/I5 in vivo and in vitro.

A modeling approach for compounds affecting body composition.

Body composition and body mass are pivotal clinical endpoints in studies of welfare diseases. We present a combined effort of established and new mathematical models based on rigorous monitoring of energy intake (EI) and body mass in mice. Specifically, we parameterize a mechanistic turnover model based on the law of energy conservation coupled to a drug mechanism model.

In vivo imaging of lipid storage and regression in diet-induced obesity during nutrition manipulation.

Changes in adipose tissue distribution and ectopic fat storage in, liver and skeletal muscle tissue impact whole body insulin sensitivity in both humans and experimental animals. Numerous mouse models of obesity, insulin resistance, and diabetes exist; however, current methods to assess mouse phenotypes commonly involve direct harvesting of the tissues of interest, precluding the possibility of repeated measurements in the same animal. In this study, we demonstrate that whole body 3-D imaging of body fat composition can be used to analyze distribution as well as redistribution of fat after intervention by repeated assessment of intrahepatocellular lipids (IHCL), intra-abdominal, subcutaneous, and total adipose tissue (IAT, SAT, and TAT) and brown adipose tissue (BAT).

The metabotropic glutamate mGluR5 receptor agonist CHPG stimulates food intake.

The metabotropic glutamate receptor 5 (mGluR5) has been suggested to modulate energy balance. For example, mGluR5 antagonists inhibit food intake in rodents and mGluR5 knockout mice resist diet-induced obesity. However, nonspecific effects can reduce food intake.

Central NMU signaling in body weight and energy balance regulation: evidence from NMUR2 deletion and chronic central NMU treatment in mice.

To investigate the role of the central neuromedin U (NMU) signaling system in body weight and energy balance regulation, we examined the effects of long-term intracerebroventricular (icv) infusion of NMU in C57Bl/6 mice and in mice lacking the gene encoding NMU receptor 2. In diet-induced obese male and female C57BL/6 mice, icv infusion of NMU (8 microg x day(-1) x mouse(-1)) for 7 days decreased body weight and total energy intake compared with vehicle treatment. However, these parameters were unaffected by NMU treatment in lean male and female C57BL/6 mice fed a standard diet.

Intestinal, adipose, and liver inflammation in diet-induced obese mice.

Chronic inflammation and increased visceral adipose tissue (VAT) are key elements of the metabolic syndrome. Both are considered to play a pathogenic role in the development of liver steatosis and insulin resistance. The aim of the present study was to investigate the hypothesis that an inflamed intestine, induced both by diet and chemical irritation, could induce persistent inflammation in VAT.

Opposing effects of adiponectin receptors 1 and 2 on energy metabolism.

The adipocyte-derived hormone adiponectin regulates glucose and lipid metabolism and influences the risk for developing obesity, type 2 diabetes, and cardiovascular disease. Adiponectin binds to two different seven-transmembrane domain receptors termed AdipoR1 and AdipoR2. To study the physiological importance of these receptors, AdipoR1 gene knockout mice (AdipoR1(-/-)) and AdipoR2 gene knockout mice (AdipoR2(-/-)) were generated.

Variations in opioid peptide levels during the estrous cycle in Sprague-Dawley rats.

The estrous cycle, with its various hormonal conditions, may provide us with the means of understanding how endocrine states relate to opioid mechanisms. There has been increasing experimental support for interaction between sex steroids and opioid peptides in the central nervous system. Here, we describe fluctuations in endogenous brain immunoreactive (ir) peptide levels during various phases of the estrous cycle in the female Sprague-Dawley rat.

Melanin-concentrating hormone receptor 1 deficiency increases insulin sensitivity in obese leptin-deficient mice without affecting body weight.

The hypothalamic peptide melanin-concentrating hormone (MCH) plays important roles in energy homeostasis. Animals overexpressing MCH develop hyperphagia, obesity, and insulin resistance. In this study, mice lacking both the MCH receptor-1 (MCHr1 knockout) and leptin (ob/ob) double-null mice (MCHr1 knockout ob/ob) were generated to investigate whether the obesity and/or the insulin resistance linked to the obese phenotype of ob/ob mice was attenuated by ablation of the MCHr1 gene.

Rats with steroid-induced polycystic ovaries develop hypertension and increased sympathetic nervous system activity.

Background: Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder associated with ovulatory dysfunction, abdominal obesity, hyperandrogenism, hypertension, and insulin resistance.

Methods: Our objectives in this study were (1) to estimate sympathetic-adrenal medullary (SAM) activity by measuring mean systolic blood pressure (MSAP) in rats with estradiol valerate (EV)-induced PCO; (2) to estimate alpha1a and alpha2a adrenoceptor expression in a brain area thought to mediate central effects on MSAP regulation and in the adrenal medulla; (3) to assess hypothalamic-pituitary-adrenal (HPA) axis regulation by measuring adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels in response to novel-environment stress; and (4) to measure abdominal obesity, sex steroids, and insulin sensitivity.

Results: The PCO rats had significantly higher MSAP than controls, higher levels of alpha1a adrenoceptor mRNA in the hypothalamic paraventricular nucleus (PVN), and lower levels of alpha2a adrenoceptor mRNA in the PVN and adrenal medulla.

Effects of maternal separation on voluntary ethanol intake and brain peptide systems in female Wistar rats.

In previous studies, changes in adult ethanol intake after early environmental experiences, such as short and prolonged maternal separation, have been described in male rats. The aim of this study was to further investigate long-term effects of maternal separation on voluntary ethanol intake as well as brain opioid and nociceptin/orphanin FQ (N/OFQ) peptides in female Wistar rats. During postnatal days (PNDs) 1-21, rat pups were subjected to 15 min (MS15) or 360 min (MS360) of daily maternal separation, or were kept under normal animal facility rearing (AFR) conditions.

Maternal separation has no effect on voluntary ethanol intake in female Wistar rats.

Adverse experiences, early in life or during adulthood, can increase the vulnerability for development of drug dependence. Investigators have shown that short and prolonged periods of maternal separation during the postnatal period can affect voluntary ethanol intake in male rats. Recent study findings have indicated sex-dependent effects of maternal separation, and, in the current study, the effects of maternal separation on acquisition of voluntary ethanol intake in female Wistar rats were investigated.

Long-term effects of short and long periods of maternal separation on brain opioid peptide levels in male Wistar rats.

Environmental manipulations early in life may induce persistent alterations in adult behaviour and physiology. The underlying neural mechanisms of these responses are not yet clear. We have previously reported long-term changes in brain opioid peptide levels in male and female Sprague-Dawley rats after short periods (15 min, known as neonatal handling) of maternal separation (MS) until weaning.

Long-term effects on brain opioid and opioid receptor like-1 receptors after short periods of maternal separation in rats.

Short periods of maternal separation of neonatal rats are known to induce attenuated behavioural and neuroendocrine responses to stress in adult life. The present study was carried out to evaluate whether 15 min separation from the dam during postnatal days 1-21 (MS15) can induce long-term changes in brain opioid (kappa- and delta-receptors) and opioid receptor-like 1 (ORL1) densities in male Sprague-Dawley rats. Receptor autoradiography indicated that MS15 rats had increased delta-receptor density in the basomedial amygdala compared to animal facility reared rats 2 months after MS15.

Effects of melanocortin receptor ligands on ethanol intake and opioid peptide levels in alcohol-preferring AA rats.

Melanocortin (MC) peptides are suggested to play a role in opiate dependence, where they antagonise the addictive properties of opiates. To further study the involvement of the MCs in drug dependence, we analysed the effects of the MC(4)-receptor antagonist HS014 (1 nmol/rat), and the non-selective MC-receptor agonist MTII (1 nmol/rat), using i.c.

Effects of maternal separation on brain nociceptin/orphanin FQ peptide levels in male Wistar rats.

Environmental manipulation early in life may induce persistent alterations in adult behaviour and physiology. In this study, we investigated the long-term effects of daily maternal separation, Days 1-21, on brain immunoreactive nociceptin/orphanin FQ (ir-N/OFQ) levels in male Wistar rats. The rat pups were separated in litters for 360 min (MS360) or 15 min (H15).

Nociceptin/orphanin FQ tissue concentration in the rat brain. Effects of repeated ethanol administration at various post-treatment intervals.

The aim of this study was to study short- and long-term effects of repeated ethanol administration on nociceptin/orphanin FQ (N/OFQ) tissue concentrations in rat brain with radioimmunoassay. Animals were given either ethanol (intraperitoneal) or saline for 13 consecutive days. N/OFQ levels were examined at 30 min, 5 days and 21 days after the last dose on day 13.